Answer:
Rubidium Sulfide, Rb2S
Step-by-step explanation:
The name is usually just the first element, and if it's not a polyatomic, then just the second element with -ide at the end. RbS = Rubidium sulfide
Rb has a +1 charge, while S has a -2, which doesn't = 0 in charges, therefore you do a cross motion with the charges
- Rb (+1) moves to the bottom of S, leaves it at S
- S (-2) moves to the bottom of Rb, making it Rb2
= Rb2S